Railway traffic controlling apparatus



y 1932- H. A. WALLACE 1,857,112

RAILWAY TRAFFIC CONTROLLING APPARATUS I Original Filed Nov. 17, 1930 4Sheets-Sheet 1 IN VEN TOR.

H,P ,l/1 a/Z.ac,6,

1 N44 ATTORNEY.

May 3, 1932. H. A. WALLACE 1,857,112

RAILWAY TRAFFIC CONTROLLING APPARATUS Original Filed Nov. 17, 1950 4Shets-Sheet 2 INVENTOR.

H'h'H al/aae,

M; ATTORNEY.

y 1932- H. A. WALLACE 1,857,112

RAILWAY TRAFFIC CONTROLLING APPARATUS Original Filed Nov. 17, 1930 4Sheets-Sheet 3 Liam N' v ATTORNEY.

May 3, 1932. H. A. WALLACE 1,857,112

RAILWAY TRAFFIC CONTROLLiNG APPARATUS I Original Filed Nov. 17, 1930 4Sheets-Sheet 4 E d INVENTOR. Hg 1.

A A ATTORNEY.

Patented May 3, 1932 untre- STATES Artur OFFICE HERBERT A. WALLACE, orEDGEWOOD nonouen, rENNsYLvAN A, AssIGNoR TO THE UNION swrrcn &. SIGNALCOMPANY, or swrssvnnn,.rE NsYLva r A connonA- TION or PENNSYLVANIA'RAILW'AY TRAFFIC CONTEOLLIN'Q APPARATUS Application filed November 17,1930, Serial No. 495,130. .Renewed October 2, 1931.

The accompanying Figures 1", 1 1 and 1 when placed end to end in theorder named with liig l onthe left, form a diagrammatic view showing oneform of apparatus embodying my invention when applied to a stretch ofsingle track railway that includes a passing siding designated in thedrawings by the reference character PS. In describing my invention, Ishall assume the left-hand end of each figure to be west and therighthand end to be east and I shall speak of a train traveling from theright to the left as a westbound train and one traveling from the leftto the right as an eastbound train. Also, at certain points in thedescription I shall refer to the apparatus shown in Fig. 1

as being assoc ated with the track section to the left of location A ofFig. 1 In the followingdescription, reference is made to theaccompanying figures wherein like characters of reference designatecorresponding parts: the numeral 1 being prefixed to the referencecharacter. when the part is associated with westbound traffic and thenumeral 2 being prefixed to the reference character when the part isassoc ated with eastbound trafii'c. Also an exponent is added to thereference character to designate the location of the part. I

The traffic rails 1 and 2 are arranged in track sections DA, AB, 13-0and CD by the usual insulated rail joints 3. It will be understood thatother arrangements of track sections other than that herein disclosedmay be employed without departing from the spirit and scope of myinvention.

Energy for the operation of the apparatus is supplied by the linetransformer one of which is located at each junction ofadjacent tracksections. The, primary 4 of each line transformer is connected to thetransmission line E which is constantly supplied with al ternatingcurrent of any convenient commerrect. current for the operation ofcertain parts of the apparatus, j

A coded transmitter CT is located at each junction of adjacenttracksections and its motor element 8 is-supplied with current from theassociated rectifier N by the wires B1 and C1. This code transmitter isto be of anyof the standard'types commonly usedin code systems and ashere shown it will be under.- stood that'the upper contact 9periodically closes its contact at a rate taken in this description tobe 180 times per minute, and that the lower contact 10 closes itscontact at the rate here taken as 80 times per minute, although anyother rates of interruption could equally as well be employed.

Each track section is provided with a track circuit which includes acode feeding track transformer T and a code following track relay TRlocated at each end of the track section. The alternatingcurrentsuppliedto the rails by each tracktransformer T is constantly coded orperiodically interrupted at the rate of 80 or 180 cycles per minute, orany other code frequency desired, and the coded alternating current isutilized to oper- The secondary 7 of each auxiliary trans ate the codefollowing track relays forcontrolling wayside signals. Furthermore thiscoded alternatingcurrent ,is adaptable to control train carried devicesfor governing the operation of cab signalswhere such train carrieddevices are controlled by power received inductively from therunningrai'ls such for example as that disclosed Y and claimed inLetters Patent of the United States, No. 1,773,472 filed by P. N.Bossart on the 7th day of February, 1927.

The general arrangement of all track circuits is the same. A detaileddescription of the track circuit for the section CD is submitted asbeing typical of all track circuits the rails 1 and 2 at the west end ofthe section through the current limiting reactor 14. The primary 21 oftransformer 2T is supplied with coded energy by a circuit that includesthe following elements: secondary 6 of line transformer L wire BXllO,the 180 code contact 9 of code transmitter GT wire 22, a circuitcontroller 23 operated by the mechanism of a wayside signal 2S asindicated by a dotted line and which is closed when the signal occupieseither its approach or proceed position, Wire 24, a normally closed backcontact 25 of a line relay lF to be later described, primary 21 and thecommon wire CXllO to the common terminal of the secondary 6.- In theevent signal 2S occupies a stop position, the coded alternating currentis supplied to the primary 21 from the secondary 6 by wire BXllO, 80code contact 10 of code transmitter CT wire 26, controller 23, and thenby the same circuit as traced above. The primary 27 of the tracktransformer 1T located at the west end of the section CD is suppliedwith 180 code energy by a circuit from the secondary 6 of the linetransformer L wire BX110, 180 code contact 9 of code transmitter OT Wire28, circuit controller 29 operated by the mechanism of the signal 18 andclosed when the signal occupies either the proceed or approach position,wire 30, front contact 31 of a line relay 2F when energized in a mannerto be later pointed out, primary 27 and wire CX110 to the commonterminal of the secondary 6 of L The primary 27 is supplied with 80 codealternating current by the path from wire BXllO through the 80 codecontact of code transmitter CT wire'32, controller 29 with signal 18 inthe stop position and then as before traced. It is to be noted thatnormally 180 code alternating currentis supplied to the rails of thesection C-D by the secondary 11 of the track transformer 2T located atthe east end of the section, while the track transformer 1T located atthe west end ofthe section is normally ineffective to supply current tothe rails inasmuch as its primary circuit isopened at the contact 31 ofa line relay 2F.

All track relays of my invention are preferably two element relays eachhaving one eletransformer L over the Wires BXllO and. CX110. The secondelement 16 is then con-' nected across the rails 1 and 2 through theresistor 17. The second track relay 2TB for the section CD has itselement 15 constantly supplied with alternating current from thesecondary 6 of the line transformer L While its second element 16 isconnected across the rails 1 and 2 through the resistor 18. It is to beobserved that the resistor 17 is shunted whenever the line relay lF isenergized closing its front contact 19 and that the resistor 18 isnormally shunted by a path that includes the back contact 20 of the linerelay 2F. These track relays are designed to be responsive toalternating current code impulses. It follows then that when the tracksection CD is unoccupied both track relays lTR- and 2TB are operated atthe rate of 180 or 80 cycles per minute by coded alternating cur rentsupplied to the rails by either one or the other of the tracktransformers 1T or 2T depending upon the direction of traffic as will bebrought out later in the specifications but normally they are operatedby 180 code suppliedby the transformer 2T located at the east end of thesection.

Each track relay of the section C-D conrelay 2TB is energized currentflows from the positive terminal of the rectifier N along wire B1,armature 34 in engagement with its front Contact, the right-hand half ofthe primary 33 of transformer 2X to a center tap and by Wire C1 to thenegative terminal of rectifier N When the track relay 2TB is deenergizedand armature 34 down in engagement with its back contact, the currentflows from the rectifier N through the left-hand half of the primary 33.The primary 35 of the decoded transformer 2Y is supplied also withdirect current, when the relay 2TB is energized and armature 34 raised,by a circuit that passes through the back contact 36 of the line relay2FF,'the left-hand half of the rear-112 contact :37 of the line relay2F. It follows that with the track relay QTR operated by :a codedalternating current and its armature 3e alternately in engagement withits front and back contact, that an alternating voltage is inducedin thesecondary '38 of the decoding transformer 2X the frequency of which isthe same as the frequency of operation of the track relay and thatwhenever the track relay ceases to operate no voltage is induced in thesecondary 38. Likewise with relay QTR operated by coded alternatingcurrent an al ternating voltage is induced in the secondary 39 of thedecoded transformer 2Y as'long as the line relay QF is down, Thesecondary 38 is connected to the input terminals of a rectilier 40 towhose output terminals the decoding relayQTP is connected. A portion ofthe secondary 39 of the decoding transformer 2Y is connected to :theinput terminals of a rectifier 41 to whose output terminals the decodedrelay QHP is connected. Both of these secondary circuits beingnon-tuned, it follows that with the track relay QTR alternatelyenergized and deenergized in step with either 180 code or code, both thedecoding relays QT]? and QHP are steadily energized and that when relay2TB? ceases to.

operate on code these decoded relays are deenergized. Across theterminals of secondary 39 is connected the reactor 42 and a portion ofthe reactor 42 is connected to the input terminals of the rectifier 43in series with a condenser 44. The decoding relay 2P is connected to theoutput terminals of the recti- When the relay .ZTR ceases to operate oncode the decoding relays are all deenergized. Furthermore, it will benoted that the energizing of the decoding relays 2P and QHP iscontrolled by the line relay 2F".

The track relay lTR located at the east end of the section CD will alsobe operated by the 180 code alternating current normally supplied to therails by the transformer 2T locatecL at the same end of the section.lVith the armature 34 of relay 1TB being operated on 180 code, thedecoding. relay 111 will be energized in the same manner as the decodingrelay QTP associated with the relay QTR and described above. However,under normal conditions the decoding relays lP and lHP also associatedwith the track relay lTR at times are not normally energized by theoperation .of the track relay lTRD, due to the fact that the circuitthrough the decoding transformer 'lY from the armas ture .34 of relay1TB isiopen at the front contacts 7 7 and 78of a line relay 113 Thus ata time when the track reIayITR- is being operated by a coded currentfrom the track transformer 2T it controls only the one deeachprovidedwitha second armature if), the r purpose of which will now bedescribed. The

primary 21 of theitrack transformer 2T is supplied with energy from thesecondary 6 of the line transformer L over wire BXllO, the 45 armatureof the code following track relay 2TR of the section B'C,.front contactv by 180 code alternating current supplied by the track circuit for thesection BC, then 180 code energy is also supplied to the track circuitof the section AB. In other words the code of the section BC is passedon to the track section AB andthe location B, at which only a westboundsignal is located cts as a cut sectionlocation for eastbound trailic.Likewise at location A, at which only an eastbound signal is located, tie p "imary -21 of the track transformer 1T is supplied with energy fromthe secondary 6 of the line transformer L over wire BX110,. the 45armature of the code following track relay 111, back contact 114 of theline relay 1F, wire 115, back contact 116 of relay 2V, back contactli?of line relay 2F", primary 21 and wire CXilO back to the secondary 6.Thus when the line control circuits of relays lF and 21* are set in amanner to be shortly described, to render track'transformer lTeffective, the code of the section to the left of location A is passedon to the section A-B and the location A Vance, for the directionselected. is passed on to the section in the rear of the cut section bythe code following track relay in ainanner similar to that whereby thecode following track relays lTR and QTR pass on the code at which'theyoperate. 'lVith a train shunting the track relay at a cut sectionlocation so that the relay ceases to operate on codethen the trackcircuit forthe rear section is with out coded energy.v

loo

To sum it-up thus far, coded alternating current is normally supplied tothe rails'at the east end of each section. The code following trackrelay located at the West end of the section is effective to control theoperation of the eastbound signal. The code following track relayconnected to the rails at the east end of the section normally acts asonly to control a line circuit. The track transformer located at thewest end of the section is normally ineffective to supply current to therails. At locations acting as a cut section for either or bothdirections of trafic the code of the track circuit of the section inadvance is repeated by the code following track relay in the trackcircuit for the section in the rear.

Each track section is provided with a line control circuit that includesa line relay located at each end of the section and designated by thereference character F. Taking section AB for example, the line circuitextends from the positive terminal of the rectifier N wire B1, wire 46,front contact 47 of decoding relay lTP wire 48, front contact 49 of theline relay QF of the section B-C, wire 50, front contact 51 of thedecoding relay QTP wire 52, winding of relay lF line wire 153, windingof relay QF wire 54, front contact 55 of the decoding relay QTP wire C1,common line wire 56 and the wire G1 at location B to the negativeterminal of the rectifier N A by-pass is provided around the frontcontact 55 of the relay 2T]? which includes the wire 57, front contact58 of the relay QV and wire 59 to the common wire C1. Also a by-pass isprovided around the front contact 49 of the relay EZF and the frontcontact 51 of the decoding relay QTP which by-pass includes a wire 60branching from wire 48, front contact 61 of relay 2V and wire 62 to thewire 52.

This line circuit for section A-B being normally closed, and the twoline relays QF and 1E connected in series in the circuit the relays areboth normally energized. Each track section is provided with a similarline control circuit. 0 However, the line circuit for all track sectionsat siding locations such as section C-D is normally open and its linerelays normally deenergized.

At each westbound signal location, there is provided a code followingline relay LR similar in design to the code following track relays of mysystem. Taking for example, the code following line relay LE theelementr63 is constantly supplied with non coded alternating currentfrom the secondary 6 of the line transformer L The element 64 issupplied with coded alternating current by the following line circuit:secondary 6 of the line transformer L wire BXllO, 180 code contact 9 ofthe code transmitter CT wire 65, circuit controllers 66 and 67 both ofwhich are operated by the signal 1S and closed with the signal atproceed or approach,

wire 6S,frorit contact 69 of the line relay 2F wire 70, front contact 71of decoding relay QTP line wire72, contact 73 of line relay 1F", wire74, contact 75 of decoding relay lTP element 64, wires CX110 and C1,common line wire 56 and wires Gland CXllO at the location B.to thecommon terminal of the secondary 6 of the transformer L It is to be seentherefore that normally the code following line relay LR is operated on180 code and its armature 76 therefore alternately making contact withits front and back contacts at a rate of 180 times a minute. The codefollowing line relay LR normally controls the decoding relays IF and lHPWith relay LR operated on code then direct current flows from thepositive terminal. of the rectifier N through armature 76, wire 7 9,front contact 80 of relay li the right-hand half of the primary 35 ofthe decoding transformer lY and back to the negative terminal ofrectifier N .Vith line relay LR deenergized, then the left-hand half ofthe primary 35 is energized by current that flows through the backcontact of 76, wire 81, front contact 82 of relay 1F", the lefthand halfof primary 35 and to the negative terminal of rectifier N The operationof the decoding transformer 1Y and its associated circuits isidentically the same as that'described for the decoding transformer QYand its associated circuits.

'Under traflic conditions that deenergize the line control relay 11? theprimary 35 of the decoding transformer lY is disconnected from the frontand back contacts of the armature 76 of relay LR and is connected to thefront and back contacts of the armature 34 of the track relay 1TB by theback contacts 83 and 84 of the line relay 1F". At eastbound signallocations such as location A, the code line circuit for the opposingwest bound signal 18 is carried through the several relays. To bespecific, the circuit for element 64 of code following line relay LR isalong wire 103, front contact 104 of the decoding relay 2T1, frontcontact 105 of line relay QF wire 106, front contact 107 of the decodingrelay lTP front contact 108 of t is line relay 1F line wire 109 and thenthrough the code transmitter and to the secondary of the linetransformer at the next location to the left of location A, such forinstance as location D, in a manner similar to that described for thecode line relay LR at the locationB.

At the junction of adjacent intermediate track sections and at the eastend of the passing siding there is provided directional stick relayscommonly used in absolute permissive block systems and here designatedby the reference character V with proper exponents. These stick relaysperform similar functions as that of the directional stick relays usedin standard A. P. B. systemsthat 7 tion on the left of A. As the trainapproaches crate on code with the result that the decoding the locationA, the floater track relay 1TB will eventually be shunted and cease tooprelay lTP becomes deenergized and the line control circuit for relay1F will be cut off from energy at contact 123. However, the line circuitfor lF is transferred to the code line wire 109 bya back contact124t andthis line wire 109 is connectedto positive power at the west end of thesection (see location D for illustration), through a back contact 125 ofthe 2T]? decoding relay and a front contact 126 of the directionalrel'ay2V therefore the line control circuit for relay 1F is retainedenergized and the transformer 2T remains active to supply 180 code asthe train travels the full length of the section. I

The train upon passing signal 2S shunts the track relav 2TB? and itsassociated decodingrelays 2TP 2H1 and 21 are all deenergized setting thesignal-2S at stop. The directional stick relay 2V is energized by itspick-up circuit inthe usual manner and is 'retained picked up by its"stick circuit. Relay 2F being up; the line control circuit'for thesection A-B whose connection to common has been opened at the frontcontact 55' of relay 2TP is now closed at'the' front contact 58 of thedirectional relay 2V": Also the control line circuit for the section tothe left of A alsection to the left of location A by the tracktransformer 2T through the stop position of the controller 128 and thefront contact 129 of the directional relay 2V; and thus as soon as thetrain vacates the'section to the left of A. the eastbound signal to therearof signal 2S is operated to indicate an approach indication. Thetrack transformer 2T is retained effective to supply/ 180 code to therails of section A-B during thetime the train travels'the full length ofthe section A-B in the same manner as described for the sec- 5 tion tothe left of the location A and the 180 stop. The line control circuitfor the section BC remains energized in the same manner as described forthe line circuit of section A--B as the train entered that section. Thatis, this line circuit is now cut to power through the front contact 122of relay 2V and the track transformer 2T remains effective to supplycoded current to the traflic rails to insure control of the cab signalsas the train travels the section BC. The track relay 2TB ceasing tooperate on code while the train occupies the section BG, no code issupplied to the track circuit of the section AB with the result that theeastbound signal 2S is held at stop during occupancy of A tion The codelinerelay LR which had been operated on 80 code as the train wasapproaching the passing siding PS is now out off from energy at thefront contact 134 of the decodingrelay 2T1 and thus the westbound signal1S now assumes the stop position and the code line circuit to the eastof signal 1S is now fed 80 code and the first westbound signal to therear of 155 caused to display an approach signal. The line controlcircuit for section GD remaining deenergized, thetrack transformer 2Tremains active to supply code to the track relays of the section toinsure proper control of the cab signals as the eastbound train travelsthe westbound signals to the west of the location 1 C are again cleared.

In the event signal 28 had been set at stop by some westbound trainapproaching the siding P the slgnal 2S would have displayed an approachsignal to the eastbound train and the transformer 2T would supply 80code to the rails to elfect the cab signals on 80 code' as the traintravels'the section Assuming a second eastbound train enters llO .l'ays1F and'QF are energized.

the section to the west of location A while the first eastbound trainoccupied either section AB or BC. The 80'code current fed to the railsby the track transformer 2T provides proper control of the cab signalsof this following eastbound train. In the case the second eastboundtrain passes the stop signal 28 and enters section A-B while the firsttrain occupied the section BC, no coded track circuit current beingsupplied to the rails by the transformer 2T the cab signals will bewithout control and will indicate an occupied block.

Next let us a sume a westbound train occupies section CD and that-thesignal 13 displays a stop signal as the result. As, the westbound trainenters-the section CD from the east and shunts both track relays lTR and2TB", the directional stick relay lV is picked up. The stick relay 1Vbeing picked up the line control circuit for the section CD is connectedto positive power at the front contact 127 and thereby the line relF upopens the circuit to the primary 21 of transformer 2T and thistrack'transforinerth-en becomes inactive. Line relay QF up closes thecircuit to primary 27; of the track transformer 1T which now becomesactive to supply code energy to: the'rails of CD. Furthermore, theenergization of relay 1F transfers the control of the decoding relays lPv and ll-IP from the code line relay LR to the code track relay 1TBwhile with relay 21 up the circuit to the decodingtransformerQY is openand the eastbound signal 28 set at stop. With signal 2S atstop, 80' codeis then supplied by the track transformer QT to the rails of the sectionB@ and in turn by the track relay QTR to the track transformer 2T of thesection A-B andthe eastbound signal 28 caused to assume the approachposition. As the rear of the Westbound train passed signal 28 the 80code fed to the track by transformer lT operates relay 2TB to reencrgizethe decoding relay QTP which in turn energizes the line relay QF withthe result that the track circuit east of D is transferred to the normaleastbound direction and the signal QS cleared. With coded alternatingcurrent supplied to the rails of the section C D by the tracktransformer 1T it is obvious that the train carried devices of thiswestbound train are under control of the traclr circuit. train advancesand enters the section;B-C, the shunting of the track relays ITR and QTRto deenergize. the line control circuit transfers the supply. of codedtrack current from the transforn er 2T to the transformer 1T The linecontrol circuit for line relays 1E and QF being new open and theserelays deenergized the line control circuit for the 1 section AB isopened at the contact 49 of Line relay As the westboundv relay QF andthesupply of the coded track current for the section AB transferred fromtransformer 2T to the transformer lT This transfer of the supply oftrack circuit current from the source at the east end to the source atthewest end of the section will be repeated for each? successivesections up to the next passing siding. As the F relays of each sectionbecome deenergized, they also transfer the control of the 1P and the lHPdecoding relays from the code following line 2F and the 2H? decodingrelays without control, all the opposing eastbound signals are set atstop as the westbound train enters; this stretch of single track.

As the rear of the train passes the signal 28 the 80 code fedto thetrack bytransformer 1T operates relay ITR andin turn the decoding relaylHP is energized. The

energizing of relay lHP opens the holding circuit for-the stick relay IVand with the stick relaylv down, the ZF and lF relays areagain'*deenergized. D'eenergizing 2'13 and lF transfers the control ofthe track circuit back to the transformer 2T and" thus the apparatus forthe section CD is restored to its normal condition. :However, thesignalls is caused to display an approach indication as the result of 80 codefed to the code line relay LR through the stop position of thecontroller 29 of the signal 18 It is obvious that as the westbound trainpassed the signal 1S, it is necessary for all F relays of the section B@to open in order that code current may be fed to the rails toeffect thecab signal. Thisrequirement insures that the F relays to the west ofsignal QH arein turn deenergized to set their respective eastboundsignals at stop. This operation provides a more reliable check en thesetting at. stop of the opposing signals than is now obtainedinthe'pres-ent day absolute permissive block systems.

As the westbound train enters section A-B and shunts the now activerelay lTR its associated decoded relays '1P lHP and ITP are concurrentlydeenergized with the result that the westbound signal 1S assumes thestop position. lay 1V is now picked up and retained energized in theusual manner. lVith the stick relay IV up, the line control circuitforthe sectionB-C is retained open at the back contact 130 to therebyretain the track circuit for the section BC set for westbound traflic.The line control circuit for the section A-B The directional stick reisnow held open, at contact 47 of the relay 1T1 and thus the opposingeastbound sigapproach indication at signal 1S".

tion by the transformer 1T establishing an This circuit for 1T may betraced from the secondary 6 of line transformer L along wire BX110,.80code contact 10 of GT controller 66 in stop position. contact 131 ofrelay 1V wire 132, wire 68, back contact 133, primary 27, and wire CXllOto the common terminal of 6. As the line control circuit to the relayslF and lF is retained open at the back contact 130 of the directionalrelay IV these relays remain deenergized whereby the apparatus for thesection B-C remains set for westbound trafiic. The westbound train as ittravels the section A'B has its cab signals controlled by 180 code fedto the rails by the track transformer 1T inasmuch as the track relay lTRis operated by 180 code and this relay repeats the code by its armature4.5.

Assume a second westbound train advances past the signal 1S during thetime the first train occupies the section. to the west of location A.The signal 1S displays approach and the code supplied to the trackcircuit by transformer 1T located at the west end of the sectioninfluencesthe cab signals on this following train. Should the secondtrain advance past the signal IS while the first train occupies thesection to the left of A, the signal 13 displays a stop signal'and theabsence of coded current in the rails of the section A-B leaves the cabsignal without control. That is to say, the location A acts as a cutsection for westbound traflic. Let us now assume that there is nofollowing westbound train and that the first westbound train advanceswest through the stretch of single track to the next passing siding atthe east end of which the apparatus will be similar to that shown atlocation D of Fig. 1 and which I shall use. to describe the operation.As the rear of the westbound train passes the location D, the tracktransformer lT supplies 80 code to the track circuit and this 80 codeoperates the track relay QTR which when so operated energizes thedecoding relay QTP The 80 code energy also operates the-track relaylocated at the east end of the section and the operation of this trackrelay on code energizes its lT decoding relay.

The energizing of the QT and the lT relays of the section will close theline control circuit for the line relay QF and its companthe east end ofthe sec- The energizing of; these line relays acts ion relay locatedrender active the track transformer located at the east end of thesection. As soon as the track relay at the east end of the sectionbecomes active, the normal circuits for the section are restored'and theeastbound signal 2S. is cleared. Also the energizing of the linerelayswill deenergize the westbound directional relay and thus act toreenergize the line control circuit for the next sect-ion to the east.The restoring of its line control circuit will act to restore thecircuits of this section to their normal condition and, in like manner,all the line circuits of each successive track section of the stretch ofsingle track will be restored and the eastbound signals cleared, and thewestbound signals again under the control of the coded line circuit.

To sum up, the apparatus of my invention provides normal coded trackcircuit control for the signals governing movements through the stretchof single track in one direction (eastward in the figures) and normalcoded line circuit control for the opposing signal (westward). For aneastbound movement these normal track circuits provide control of theeastbound wayside signals and coded energy for the control of cabsignals and train control devices, and deprive all westbound waysidesignals of coded line circuit control setting them at stop and leavesthe cab signals of a westbound train without coded energy. The apparatusalso provides means controlled by a westbound movement for causing allwestbound wayside signals and the cab signals of the westbound train tobe controlled by continuous coded track circuits which leave theeastward wayside signals without any control setting them at stop andwhich also deprives'eastward trains of cab signal code. V Such a systemas here provided is practically immune from foreign code and frompropulsion current as far as the track circuits are concerned. The codeline circuit insures a system free from inductive interference bycommercial transmission lines. Such a systemis adaptable to eitherwayside signals or cab signals, or both. Furthermore, such a systemprovides a'more reliable check on the protection of-head-on movementsthan is obtained in present day A. P. B. systems.

Although I have herein shown and described only one form of apparatusembody:

sing my invention, it is understood that various changes andmodifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of myinvention.

Having thus described my invention, what 1 claim is:

1. In combination, a track section, a signal located at each end of thesection to govern traflio in opposite directions through the section andeachadapted todisplay several dist-inctive indications, a source ofcurrent located at each end of the section each adapted to supplycurrent of different characteristics to the traflic rails, a track relayat eachend of the section each permanently connected to.

the trafiic rails andsresponsiveto the .diiierent characteristics ofthecurrentsupplied to the rails to selectively. govern the severalindications of the signal located at itsrespective end oi the section,and meansresponsive to the direction of traliic to selectively. renderone or the other of said sources effective to supply current to therailsand t0 render'the track relay at the same end as theeffectivesource of current ineffective to. select the. several indications ofit-srespe ive signal.

.2. In combination, a track section, a signal located at each end of thesectionto govern traflic in opposite directions throughthesection andeach adaptedtodisplay several'distinc'tive indications,.a source ofcurrentlocated at each end of the section each adapted to supplyalternating current of different codes to the traffic rails, atrackrelay at each end of the section each permanently connected totherails and responsive to coded.

alternating current, aplurality of decoding relays associated With-eachtrackrelay tose- 'lectively govern the several indications ofgthe signallocated at the same end of the section, means to selectively energizethe decoding relaysin accordance with the code operating the associatedtrack relay, and means responsive to the di "ection of traffic toselectively render one or the otherct said sources effective to supplycurrent to the rails and to render the track relay at the same end. asthe effective source of current inefiectiveto energize the associateddecodingrlays.

In combination, a stretch of tratlicirails over which traffic may movein either direction, a signal. to govern tr'afiic through the stretch, adecoding relay to govern the operation of the signal, a codefollow'ingtrack relay and a code following line relay associated withthe decoding relay and each of which is responsive to coded current, acurrent source adapted to supply coded current to saidtrack relay and tosaid line relay, and directional means to place the decoding relay underthe control of the track relay or under the control of the linerelayaccording to the direcgovern theseveral indications of the signal,'a

"- code following track relay-and a code'follo'wing line relayassociated with said decoding relays, decoding means to selectivelyenergize the decoding relays according to the-code operating theassociated track relay or line fre lay, a current source adapted tosupply coded current of diii'erent codes to said track relay and to saidline relay, directional ineansto place the decoding means underthecontrol of either the track relay or the'line relay according to thedirectionof trafiiqand circuitmeans to selectthe differentcodesinaccordstretclnra plurality of decoding relays'to s'electivelygovern the several. indications ofthe signal, acode following tract;relay and a code following line. relay associated with thedecodingrelays and each responsive'to code impulses ofalternatingcurrent, decoding means to selectively energize the decoding relaysaccordingtoithe code Qoperating the associated trackrelay or linerelay,a current source adapted to supply coded alternating current ofdifferent codes to said track relay and said linerelay,directionallneanstoplace the decoding means under thecontrolof eitherthe trackrelay or the line relay according to the directionof traffic,and circuit means to selec the diiierent codes in accordancewith trafiicconditions inadvance of the signal. 7 a

'6. In combination, a stretch of traffic rails over Whichtraflicmaymovev in either direction, a signal to govern traffic through thestretch, .a code following track relay and acode -.following line relayeach responsive to coded .current,..and said'relays arranged to;,goveri1 the operationrof the signal, a current source adapted tosupply ,coded current, I and directional means to render the currentsource efiective .to supply coded currentto either the track relay or.to .theline relay depending upon the direction of traflic. 7. Incombination, a stretchoit traliic rails .over which .traflic may move ineitherdirec- 'tion, arsignal to govern Itraflic through the stretch, adecoding relayto control the signal, arcode following track relay and acode following .Iline relay associated vvith the decodingrelay, decodingmeansto energize the decoding relay in response to .co'deioperation ofeither :the associated track :relay or line relay, a .current sourceadapted to supply coded current, and directionalimeansto Irender thesaid source effective tosupply coded current .to either the track.relayor to the line relay depending upon thedireetion of travel. r

8. In combinatioma stretchvottratficirails over vvhichitrafiic may movein either '.direc-.

tion, a signal toygovern traffic through the stretch, a decodingrelayxto control the sigroad. a code followingv track relay. andia codefollowingline relavassociated with the decoding,relay, decodingmeans toenergize the decoding relay in responseto code operation ofeither theassociated track relay or line relay, a current source adapted to supplycoded vcurrent,and directional means to renderthe said source effectiveto supplyicoded current to either the track relay 'orfto the [line relaydepending upon the direction of travel and to place the decoding meansunder'the control of the relay to which coded current is supplied. 7 V 79. In combination, a stretch of traffic rails over which trafiic maymove in either direction, a signal having several distinctiveindications to govern tratfic through the stretch, a plurality ofdecoding relays to selectively govern the severalindications of thesignal, a code following track relay and a code following line relayassociated with said decoding relays, decoding means to selectivelyenergize thedecoding relays in accordance with the code operating eitherthe associated track relay or the line relay, a

' current source adapted to supply coded ourrent of different codes,means to render the source effective to supply coded current to eitherthe track relay or to the line relay depending on the direction oftrafiic and to place the decoding means under the control of the relayto which coded'current is supplied, and circuit means to select thedifferent codes in accordance with tratfic conditions in advance of thesignal.

' 10. In combination, a stretch of traflic rails over which traflic maymove in either direction, a signal having several distinctiveindications to govern tratfic through the stretch, a code followingtrack relay and a code following line relay each responsive to codedcurrent of different codes and arranged to selectively control theseveral indications of the signal according to difierent codes, acurrent source adapted to supply coded current of diflerent codes,directional means to'render the current sourcev eflective to supplycoded current to either the track relay or to the line relay accordingto the direction of trafiic, and circuit means to select the difierentcodes in accordance with traffic conditions in advance of the signal.11. In combination, a stretch of trafiic rails over which traflic maymove in either direc tion, a signal having several distinctiveindications to govern traflic through the stretch, a plurality ofdecoding relays to selectively governthe several indications of thesignal,

a code following track relay, decoding means associated with the trackrelay to selectively energize the decoding relays accordingto the codeoperating the track relay, a current "source adapted to supply codedcurrent of different codes to thetrack'relay, means to select thedifierent codes according to trafand each adapted to supply codedcurrent to the traffic rails, a track relay located at each end otthesection connected to the traffic rails and each responsive to codedcurrent, a decoding relay associated with each track relay energized inresponse to code operations of its associated track relay, a trafficcontrolled directional control circuit, means controlled by said controlcircuit to render the current source at one end of the section effectiveto supply coded current and to render the track relay atthe opposite endof the section effective to control its decoding relay in response totraflic in one direction and to render the other current sourceeffective to supply coded current and the track relay opposite saidother source effective to control its decoding relay in response to tratnc in the other direction, and a signal controlled by each decodingrelay.

13. In combination, a first and a second track section, a track circuitfor each section, a'source of current for each track circuit, codingmeans for coding the current supplied by the source to the track'circuitof the first track section, a track relay for the track circuit of thefirst track section responsive to such coded current, a contact operatedby said track relay and included in the track circuit for the secondsection to thereby reproduce the code of the first track circuit in thesecond track circuit,'and a signal controlled by the second trackcircuit.

14. In combination, a first and a second track section, a source ofalternating current for each section, each adapted to be connectedacross the trafficrails at the exit end of its respective section,coding means to code the alternating current supplied to the traficrails of the first track section, a track relay connected across thetraflic rails at the, entrance end of the first section and responsiveto such coded alternating current, a contact for said relay included inthe connection between the source and the traflic rails of the secondsection to thereby reproduce the code of the first section in the secondsection, and a signal controlled by the coded alternating currentflowing in the rails of the second section. c

15. In combination, a first and a second track section over whichtra-liic may move in either direction, means for supplying codedcurrentof. diiiferent codes to the rails of each section, a-track relayfor each section responsive to such coded current in the rails, adirectional means, means rendered effective by the directional means inresponse to trafiic in one direction to repeat the code operating thetrack relay of the first section in the current supplied to the traflicrails of the second section, and other means rendered effective by thedirectional means in response to traflic in the other direction toselect the code to be supplied to the rails of the first secnest-r1 2tion'in accordance to th'e trafiic conditions of thesecond section.

16. In combination, a :first and asecond track section, a signal locatedat the adjacent ends of the track sections to govern tra-fiic travelingfrom the first tothe second-section, a current source-to supply codedalternating current of different codes'to the traific rails of eachtrack sectionydirectional means responsive to trafic traveling in thedirection oppositethat governed by the-signal to render the currentsource effective "to supply to the rails of the second section underall'traffic conditions alternating current ofthe same code as thatoperating thetrac-k relay of the first-section, andsaid directionalmeans responsive to trafiic in the same direction as that governed bythe signalto-render the current source efiective-tosupply to the railsof the first section alternating current of a code selectively governedby trafiic conditions in advance of the signal. 7

17. In combination, a first and a second track-section, means adapted'tosupply' coded alternating current-to thetraflic rails of eachsection,trafiic controlled means'to repeat the code supplied by saidmeans to the rails of the first section in the current supplied to therails of the second section in response to traffic in one direction andto repeat the code supplied by saidmeans tothe rails of the secondsection in thecurrent supp-lied to the rails of the first section inresponse to trafiic in illlle opposite direction, and signals controlledby the coded alternating current supplied to the trafiic rails of saidsections.

18. An absolute permissive block signaling system including, traflicrails arranged in track sections, a first and a second current sourcefor each section located at opposite ends of the sections and eachadapted to supply coded alternating current, a code following trackrelay located at each end of each section, a code following line relayfor each section and located at one end of the section; a directionalline circuit for each section responsive to traffic in one direction torender the first current source effective to supply coded current to thetwo track relays of the section and the second current source effectiveto supply coded current to the line relay of the section, and saiddirectional circuit responsive lSOlZIfililC in the other direction torender the first current source ineffective and the second sourceineffective to supply current to the line relay but efiective to supplycurrent to the two track relays of the section, and signaling meanscontrolled by said track relays and said line relays.

19. An absolute permissive block signaling system including, a stretchof single track railway arranged in track sections, an eastbound signaland a westbound signal for each section, a first and a second codefollowing track relay for each section located at opposite ends of thesection and arranged with the first'relay normally controllingtheeastbound signal of the section, a code following line relay foreachsection normally controlling'the westbound signal of the section, adirectional control circuit for each section responsiveito an eastboundtrain entering the stretch to render the linerelay of each sectionineffective to control its signal, and said directional control circuitresponsive to a westbound train entering the stretch to, render thefirst track relay of each. section ineffective to control its signal andto transfer the control of the westboundsignal from the line. relay tothe second track relay of the section, and trafiic controlled'ineans tosupply coded'currentto the two track relays andlto the code followingline relay'of each section.

20. An absolute permissive block signaling system including, a pluralityoftrack sections, a :first and second current source for-each sectionlocated at opposite ends of the sec- :tions and each adapted tosupply-coded alternating current, acodefollowing track re-Ilay'locatedrat each end of each'track section, a code followinglinerelay for each sectionand located at one end of the section;directionally controlled means for each :section under the joint controlof thetrack relays and said line relay ofthe section to render the firstsource normally effective to supply codedcur- :rent to the track atone-end and render-effective the second source to supplycurrentto .theotierend when-a train moves toward said vother.end, and means controlledby a train'to render inefiectire a source to 1 supply coded current.aliead'of: an opposingtrain.

21. Anabsolutepermissive-block signaling system including, a first and asecond track section, a first and a second current source forIeaehsection located at opposite ends of'the section andueach adapted tosupply coded :alternating current to the section, a normallyclosed-directional line circuit 'fOPthe first section opened by trafiicentering said firstsection 'in one direction, a normally closeddirectional line circuit for the second section opened byrtrafiicentering said'second seetion in oned-irectioni and by opening thedirectionval-line circuit of saidfirstsection,and means .ingsystemincluding, a first and asecond track section, a first and a secondcurrent III source for each section located at: opposite vI ends of thesection andeach adapted to supply coded-alternatingcurrent to thesection,

a normally closeddirectional line circuit,

forfithe first :section opened by traflic enter-' ting said firstsection in one direction, a nor- :m-ally closed LdlI'GCtlOIIal vlinecircuit for the second section opened bytraffic entering saidsecondsection in one direction and by opening the directional linecircuit oi said first section, means controlled by said directional linecircuits for removing the source of coded current of said second sectionnearest the'train and for applying the source of coded current at thefarthest end of said second section. V

23. A stretch of single track railroad in cluding, aplurality o1 signalsfor governing train moments in each direction, track sections, means forsupplying coded current to the east end of each track section, a trackrelay at the west end of each track section responsive to the codedelivered to the east end, a line circuit for each track section, meansfor supplying coded current to said line circuit at the west end, a linerelay at the east end of each section responsive to the code deliveredto the line circuit, means for normally governing eastbound signalsbysaid track relays and for governing westbound signals by said linerelays, and means for depriving said track circuits of coded current ifa train enters thestretch from the east and for depriving said linecircuits of coded current if a train enters said stretch from the west.i p

24. A stretch of single track railroad including, a plurality of signalsfor governing train movements in each direction, track sections, meansfor supplying coded current to the east end of each track section, atrack relay at the west end ofeach track section responsive to the codedelivered to the east end, a line circuit for each track section, meansfor supplying coded current to said line circuit at the west end, a linerelay at the east end resp'onsivetothe code delivered to the linecircuit, means for normally governing; said westbound sign'alsby trackrelays and for governing westbound signals by said line relay, anddirectional means for governing said westbound signals by track relaysand for deenergizing said line relays.

25. A stretch of single track railroad arranged in track sections, adirectional line circuit for each section, a source at the east end ofeach section to normally supply current to the directional line circuitof the section, means responsive to a train entering a section at theeast'end to disconnect the sourcefrom the directional line circuit ofthe section, means responsive to an east-bound train to disconnect thesource ranged in track sections, a directional line circuit for eachsection including a line relay at each end of the section, a source ofcurrent, a source at the east end of each section to normally supplycurrent to the directional line circuit of the section, means responsiveto a train entering a section at the east end to disconnect thesourcefrom the directional line circuit of the section, means responsive to aneastbound train entering the section to disconnect the source at theeast end from the directional line circuit and to connect a source atthe westend of the section to the directional line circuit, and signalsto govern traflic in opposite directions controlled by the said linerelays,

27, A stretch of-single trackrailroad arranged in track sections, afirst line circuit for each section,'a source at the west end of eachsection to normally supply the said line circuit with coded current, aline relay at the east end ofeach track section connected to the linecircuit and responsive to such coded current, a directional line circuitfor each section, a source at the east end of each section to normallysupply current to said directional line circuit; means responsive to aneastbound train to disconnect the source of coded current from the firstline circuit HERBERT A. WALLACE.

